This invention relates generally to vertical blade rotary air classifying and separating apparatus. Such devices are used to classify and separate particles (such as mineral particles) according to their size, and produce separate discharges of coarse and fine particulate materials. More specifically the invention relates to an improvement in such apparatus, wherein a deflector is incorporated into same to reduce wear to the rotor and associated components caused by abrasive impact with air entrained feed materials.
Vertical blade rotary air classifiers are well known to industry for use in separating dry granular materials (such as minerals) according to particle size. In a typical configuration, dry granular material is entrained in an air stream induced by a fan arrangement, and the entrained material is presented to a vertical blade rotary rejector. The entrained fine fraction of the material passes through the rotating vertical blade rejector to a conduit which directs it to a collection device. The coarse fraction of the materials is prevented from passing through the rotary rejector by impact with the vertical rejector blades, and is forced away for collection or for further processing.
Collision of the entrained feed material with the rotating vertical rejector blades subjects the component parts of the rejector cage to severe abrasion. The vertical blades and the lower rotor support section of the vertical blade rotary rejector cage are subjected to the most severe abrasion. In the past this abrasion problem in respect to the rotor rejector blades has typically been addressed by constructing the blades from an abrasion resistant material, or by coating the leading side of the blades with an abrasion resistant material. The abrasion problem in respect to the bottom support members of the rotating rejector cage has typically been addressed by attaching some type of protecting shield or deflector to the bottom support member of the rotor to protect the components in the lower part of the rotor from the effects of material abrasion. Since, however, this type of shield rotates with the rotor, the abrasion problem is shifted from the lower rotor to the rotating deflector. If the wear is not detected and holes are allowed to develop in the rotating deflector, material will enter the deflector cavity, lodge against the inside walls of same and upset the balance of the rotating assembly of the classifier. Rotating deflectors also impart centrifugal force to particles colliding with them. This centrifugal force drives the particles against the wall of the classifying chamber and back into the rotating rejector blades causing abrasive wear to the blades.
In accordance with the foregoing, it may be regarded an object of the present invention, to provide an improved air classifying apparatus of the type utilizing vertical blade rotors, which is effective in preventing or limiting damage of the downwardly facing rotor support plate.